MMET 206 Exam 2 Module 4: Engineering & Specialty Plastics

Plastic Alloys

A mixture of 2 or more polymers

Alloys of Polystyrene (PS)

HIPS, SAN, ABS

ABS (Acrylonitrile Butadiene Styrene)

Most commonly used 3D printing material; primary feature is excellent impact resistance

Properties of Acrylonitrile monomer

Weather resistance, barrier properties, strength

Properties of Styrene monomer

Heat/chemical resistance, rigidity, transparency, stiffness, low cost

Properties of Butadiene monomer

Toughness, elongation, low temp properties, mechanical strength

Engineering plastics vs commodity plastics

Better thermal properties, better chemical resistance, high strength and stiffness to weight ratios

Polyamide (PA) properties

High stiffness, fatigue/creep resistance, strongest plastic

Polyoxymethylene (POM) properties

High strength, toughness, low friction (used for bearings and gears)

Plastics ranked by lowest coefficient of friction

Teflon < UHMWPE < POM < HDPE

Polycarbonate (PC) applications

CDs, car lights, safety glass lenses, greenhouse panels

Polymethylmethacrylate (PMMA) property

Best light transmittance among all plastics (92%)

PMMA applications

Aircraft windows, hockey rink shields, bulletproof glass

Polyimide (PI) property

Most heat-resistant plastic

PEEK property

Up to 100x longer fatigue life and 20% greater specific strength/stiffness than Aluminum 7075-T6

Most consumed engineering thermoplastics in US

1. PC 2. PA 3. Polyester 4. POM

Thermoset Characteristics

Stiffer and more brittle than thermoplastics, better creep resistance, low viscosity allows complex shapes, superior fiber wetting

Foam plastics main application

Thermal insulation

Open cell foam plastics

Flexible (e.g., sound absorbers, silica aerogel)

Closed cell foam plastics

Rigid (e.g., structural thermal insulation)

3 most common foam plastics

Polystyrene (PS), Polyurethane (PU), Polyethylene (LDPE)

Polystyrene (PS) foam applications

STYROFOAM, packaging, flotation, thermal insulation

Polyurethane (PU) foam applications

Bed and upholstery, packaging, flotation, thermal insulation

Aerogel

Lightest and lowest-density solid known; made of open-cell silica foam; best thermal insulator (better than air)